If the form parameter is already the active MDI child form, then the Form.ActivateMdiChild(Form) method simply returns. If form is not null, then it is set to be the active MDI child form.

Whether the form parameter is null or not, Form.ActivateMdiChild(Form) raises the Form.MdiChildActivate event.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0